1. Field of the Invention
The present invention relates to a substrate processing system and a substrate processing method.
2. Description of the Related Art
In the photography in processes of semiconductor device fabrication, for example, resist coating treatment for forming a resist film on the surface of a semiconductor wafer (described as xe2x80x9ca waferxe2x80x9d hereinafter), exposing processing for exposing the wafer by irradiating a pattern thereon, developing treatment for developing the exposed wafer, and the like are performed. Processing units for performing such processing and treatments are integrated into one system to form a coating and developing system.
Incidentally, it is important for the resist film, which is coated on the wafer before the exposing processing of a pattern, to have a predetermined film thickness in order to suitably perform predetermined lithography. Therefore, the film thickness of the resist film on the wafer is inspected before the pattern is exposed, and when it is over a predetermined allowable value, the rotational frequency of the wafer in a coating unit, for example, is controlled based on the inspection.
Conventionally, an operator selects a wafer before exposing processing out of the coating and developing system to perform the inspection of the film thickness of the resist film with use of a film thickness measuring unit for inspection provided separately from the coating and developing system.
However, it is necessary to transfer the wafer from the coating and developing system to the unit for inspecting the film thickness in such a manner, thus requiring both labor and time. Further, there is a danger that the wafer is contaminated while being transferred. Furthermore, there is a risk that an operator drops the wafer by mistake.
The present invention is made in view of the aforesaid points and its object is to inspect the film thickness of the resist film on the wafer in the single system by providing film thickness measuring means in a peripheral aligner in which the existing mechanism in the coating and developing system can be utilized.
A first aspect of the present invention is a processing system for processing a substrate, comprising a coating unit for coating the substrate with a treatment solution and a peripheral aligner having a mounting table rotatable and movable in at least one direction and irradiating the peripheral portion of the substrate on the mounting table with light from an irradiating portion to expose a coating film on the substrate, the peripheral aligner having film thickness measuring means provided with a sensor member for measuring the film thickness of the coating film.
A second aspect of the present invention is a method of processing a substrate with use of a substrate processing system, the substrate processing system comprising a peripheral aligner for irradiating the peripheral portion of the substrate with light to expose a coating film applied on the substrate and a unit for measuring a film thickness of the coating film, the method comprising the step of irradiating the peripheral portion of the substrate with the light to expose the coating film after measuring the film thickness of the coating film on the substrate. In this case, the step of measuring the film thickness of the coating film once again may be added after the coating film is exposed.
A third aspect of the present invention is a process of performing processing on a substrate with use of a substrate processing system comprising a peripheral aligner, a unit for measuring a film thickness of a coating film, and further a coating unit for coating the substrate with the coating film, the process comprising the steps of using a test substrate as the substrate of which film thickness is measured, performing predetermined coating treatment on a production substrate in the coating unit when a measurement value is within an allowable range as a result of a measurement of the film thickness, and measuring the film thickness of another test substrate subjected to coating treatment in the coating unit after making a necessary correction to the coating unit when the measurement value is out of the allowable range.
According to the present invention, the peripheral aligner has a mounting table rotatable and movable in at least one direction. Therefore, it is possible to suitably perform a film thickness measurement at, for example, a predetermined point on the substrate by utilizing such mechanism, and in addition it is not necessary to provide a unit having the film thickness measuring means separately from the substrate processing system.
In the substrate processing method according to the present invention, the film thickness measurement and peripheral exposure are performed using the same substrate processing system, whereby it is not necessary to perform the film thickness measurement in another unit which is separately provided. Moreover, since the coating film on the peripheral portion of the substrate is exposed after the film thickness of the coating film on the substrate is measured, it is possible to measure the film thickness of the coating film before peripheral exposing processing, which can be material for determining whether preceding treatment is properly performed or not.
In the substrate processing method according to the present invention, a substrate exclusive to test is housed in a cassette beforehand separately from, for example, a production substrate, more specifically, a substrate which undergoes predetermined processing to be shipped as a product, and the film thickness is initially measured with the test substrate before coating treatment or subsequent processing is performed on the production substrate. Then, predetermined coating treatment is subsequently performed on the production substrate in the coating unit when the measurement value is within the allowable range. On the other hand, when the measurement value is out of the allowable range, another test substrate is taken out of the cassette, then subjected to coating treatment in the coating unit and the film thickness thereof is measured after a necessary correction is made to the coating unit. As a result of the measurement, when the film thickness is within the allowable range, processing is performed on the production substrate, and when the film thickness is out of the allowable range, the correction is again made to the coating unit and thereafter other test substrates are subsequently measured the film thickness thereof. As a consequence, the yield of the production wafer can be improved. The above-described film thickness measurement with the test substrate may be periodically performed in a break of a lot of the production substrates, or after processing is performed on a predetermined number of the production substrates.